One of the things i really like in AOS 3.9 is WorkBench. It has been greatly improved since AOS 3.5 and i use it as my standard desktop. I'm not running ScalOS or Dopus.
@A4000_Mad
If you are talking about DefIcons, there is nothing OS3.9 specific about it. It's a 3rd party tool, freely available from Aminet
Edit: No. Sorry for the confusion. DefIcons is something different.